Anyone know of a cheaper but still decent way to mount a scope on a AR with a fixed front sight? I bought a scope to play around with to see if I want to go build towards that direction and am curious if there is a preferred way to mount a scope when using a fixed front sight? I have seen risers, but I was curious if anyone makes mounts for this application?

It's not cheaper than a riser and rings, but American Defense, Bobro, or LaRue all make excellent one piece scope mounts specifically for the AR-15. They are all quick detach, and give you the perfect height for your proper cheekweld.

what magnification is the scope. anything with the slightest magnification like 2.5x for example and you wont even notice the FSB. I have a 3-9 on one rifle with a standard FSB and at 3x you don't see it. On my other one with a 2.5x you see just a very faint blur but i see right past it. This was using a Larue Lt104 mount on the 2.5x and standard high rings on the 3x.

It isn't just a matter of raising the scope to be above the front sight. You only want the scope to be as high as it NEEDS to be to give you a proper cheek weld and, if necessary, clear a BUIS. As mentioned before, the front sight base isn't a problem if the scope is around a 3X or better. I could barely see the FSP when looking through my TA33 ACOG which is a 3X.

The PEPR is a petty nice mount, but it is not a quick detachable; so, every time you take it off, you'll likely have to make at least minor adjustments to sight the scope in again. That is, unless you use a torque wrench to be sure to use the same amount of torque every time you remount the scope. If you want to go on the cheap and wind up with a set of parts that you'll likely be able to use in the future, you have a couple of options.

First, if you are using a standard A2 stock and/or you don't need to push the scope forward to a point where the front ring will be off of the upper, you could just get a set of ultra high rings. I like the ones from Warne, although they are on the pricey side at about $60 for a set. If you need some sort of cantilever setup to get the scope forward over the upper, you can use a Yankee Hill 5" extension riser and a set of high rings. This rig comes to about $70. I keep a couple of these on hand just in case. With these, you can accommodate almost any setup that you might need. The extension risers also come in longer versions if you need them.

I used one of those extension risers on the rifle on the top. I used medium rings on this monstrosity and they were a little too short.